// SPDX-License-Identifier: GPL-2.0/* * queue_stack_maps.c: BPF queue and stack maps * * Copyright (c) 2018 Politecnico di Torino */#include <linux/bpf.h>#include <linux/list.h>#include <linux/slab.h>#include "percpu_freelist.h" #define QUEUE_STACK_CREATE_FLAG_MASK \	(BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY)  struct bpf_queue_stack {	struct bpf_map map;	raw_spinlock_t lock;	u32 head, tail;	u32 size; /* max_entries + 1 */ 	char elements[0] __aligned(8);}; static struct bpf_queue_stack *bpf_queue_stack(struct bpf_map *map){	return container_of(map, struct bpf_queue_stack, map);} static bool queue_stack_map_is_empty(struct bpf_queue_stack *qs){	return qs->head == qs->tail;} static bool queue_stack_map_is_full(struct bpf_queue_stack *qs){	u32 head = qs->head + 1; 	if (unlikely(head >= qs->size))		head = 0; 	return head == qs->tail;} /* Called from syscall */static int queue_stack_map_alloc_check(union bpf_attr *attr){	/* check sanity of attributes */	if (attr->max_entries == 0 || attr->key_size != 0 ||	    attr->map_flags & ~QUEUE_STACK_CREATE_FLAG_MASK)		return -EINVAL; 	if (attr->value_size > KMALLOC_MAX_SIZE)		/* if value_size is bigger, the user space won't be able to		 * access the elements.		 */		return -E2BIG; 	return 0;} static struct bpf_map *queue_stack_map_alloc(union bpf_attr *attr){	int ret, numa_node = bpf_map_attr_numa_node(attr);	struct bpf_queue_stack *qs;	u32 size, value_size;	u64 queue_size, cost; 	size = attr->max_entries + 1;	value_size = attr->value_size; 	queue_size = sizeof(*qs) + (u64) value_size * size; 	cost = queue_size;	if (cost >= U32_MAX - PAGE_SIZE)		return ERR_PTR(-E2BIG); 	cost = round_up(cost, PAGE_SIZE) >> PAGE_SHIFT; 	ret = bpf_map_precharge_memlock(cost);	if (ret < 0)		return ERR_PTR(ret); 	qs = bpf_map_area_alloc(queue_size, numa_node);	if (!qs)		return ERR_PTR(-ENOMEM); 	memset(qs, 0, sizeof(*qs)); 	bpf_map_init_from_attr(&qs->map, attr); 	qs->map.pages = cost;	qs->size = size; 	raw_spin_lock_init(&qs->lock); 	return &qs->map;} /* Called when map->refcnt goes to zero, either from workqueue or from syscall */static void queue_stack_map_free(struct bpf_map *map){	struct bpf_queue_stack *qs = bpf_queue_stack(map); 	/* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,	 * so the programs (can be more than one that used this map) were	 * disconnected from events. Wait for outstanding critical sections in	 * these programs to complete	 */	synchronize_rcu(); 	bpf_map_area_free(qs);} static int __queue_map_get(struct bpf_map *map, void *value, bool delete){	struct bpf_queue_stack *qs = bpf_queue_stack(map);	unsigned long flags;	int err = 0;	void *ptr; 	raw_spin_lock_irqsave(&qs->lock, flags); 	if (queue_stack_map_is_empty(qs)) {		memset(value, 0, qs->map.value_size);		err = -ENOENT;		goto out;	} 	ptr = &qs->elements[qs->tail * qs->map.value_size];	memcpy(value, ptr, qs->map.value_size); 	if (delete) {		if (unlikely(++qs->tail >= qs->size))			qs->tail = 0;	} out:	raw_spin_unlock_irqrestore(&qs->lock, flags);	return err;}  static int __stack_map_get(struct bpf_map *map, void *value, bool delete){	struct bpf_queue_stack *qs = bpf_queue_stack(map);	unsigned long flags;	int err = 0;	void *ptr;	u32 index; 	raw_spin_lock_irqsave(&qs->lock, flags); 	if (queue_stack_map_is_empty(qs)) {		memset(value, 0, qs->map.value_size);		err = -ENOENT;		goto out;	} 	index = qs->head - 1;	if (unlikely(index >= qs->size))		index = qs->size - 1; 	ptr = &qs->elements[index * qs->map.value_size];	memcpy(value, ptr, qs->map.value_size); 	if (delete)		qs->head = index; out:	raw_spin_unlock_irqrestore(&qs->lock, flags);	return err;} /* Called from syscall or from eBPF program */static int queue_map_peek_elem(struct bpf_map *map, void *value){	return __queue_map_get(map, value, false);} /* Called from syscall or from eBPF program */static int stack_map_peek_elem(struct bpf_map *map, void *value){	return __stack_map_get(map, value, false);} /* Called from syscall or from eBPF program */static int queue_map_pop_elem(struct bpf_map *map, void *value){	return __queue_map_get(map, value, true);} /* Called from syscall or from eBPF program */static int stack_map_pop_elem(struct bpf_map *map, void *value){	return __stack_map_get(map, value, true);} /* Called from syscall or from eBPF program */static int queue_stack_map_push_elem(struct bpf_map *map, void *value,				     u64 flags){	struct bpf_queue_stack *qs = bpf_queue_stack(map);	unsigned long irq_flags;	int err = 0;	void *dst; 	/* BPF_EXIST is used to force making room for a new element in case the	 * map is full	 */	bool replace = (flags & BPF_EXIST); 	/* Check supported flags for queue and stack maps */	if (flags & BPF_NOEXIST || flags > BPF_EXIST)		return -EINVAL; 	raw_spin_lock_irqsave(&qs->lock, irq_flags); 	if (queue_stack_map_is_full(qs)) {		if (!replace) {			err = -E2BIG;			goto out;		}		/* advance tail pointer to overwrite oldest element */		if (unlikely(++qs->tail >= qs->size))			qs->tail = 0;	} 	dst = &qs->elements[qs->head * qs->map.value_size];	memcpy(dst, value, qs->map.value_size); 	if (unlikely(++qs->head >= qs->size))		qs->head = 0; out:	raw_spin_unlock_irqrestore(&qs->lock, irq_flags);	return err;} /* Called from syscall or from eBPF program */static void *queue_stack_map_lookup_elem(struct bpf_map *map, void *key){	return NULL;} /* Called from syscall or from eBPF program */static int queue_stack_map_update_elem(struct bpf_map *map, void *key,				       void *value, u64 flags){	return -EINVAL;} /* Called from syscall or from eBPF program */static int queue_stack_map_delete_elem(struct bpf_map *map, void *key){	return -EINVAL;} /* Called from syscall */static int queue_stack_map_get_next_key(struct bpf_map *map, void *key,					void *next_key){	return -EINVAL;} const struct bpf_map_ops queue_map_ops = {	.map_alloc_check = queue_stack_map_alloc_check,	.map_alloc = queue_stack_map_alloc,	.map_free = queue_stack_map_free,	.map_lookup_elem = queue_stack_map_lookup_elem,	.map_update_elem = queue_stack_map_update_elem,	.map_delete_elem = queue_stack_map_delete_elem,	.map_push_elem = queue_stack_map_push_elem,	.map_pop_elem = queue_map_pop_elem,	.map_peek_elem = queue_map_peek_elem,	.map_get_next_key = queue_stack_map_get_next_key,}; const struct bpf_map_ops stack_map_ops = {	.map_alloc_check = queue_stack_map_alloc_check,	.map_alloc = queue_stack_map_alloc,	.map_free = queue_stack_map_free,	.map_lookup_elem = queue_stack_map_lookup_elem,	.map_update_elem = queue_stack_map_update_elem,	.map_delete_elem = queue_stack_map_delete_elem,	.map_push_elem = queue_stack_map_push_elem,	.map_pop_elem = stack_map_pop_elem,	.map_peek_elem = stack_map_peek_elem,	.map_get_next_key = queue_stack_map_get_next_key,};